Cryptosporidium spp. and Toxoplasma gondii are also Category B biothreat agents because their infectious forms resist chemical inactivation and can be easily harvested and introduced into food and water supplies. Cryptosporidium are a major cause of prolonged and disabling diarrhea and Toxoplasma can cause a serious illness upon primary infection that is particularly dangerous to pregnant women. There is only one FDA- approved drug for cryptosporidiosis, and its efficacy is controversial. Therapeutic options for Toxoplasma are limited by toxicity. The C. parvum and T. gondii calcium dependent protein kinase 1 (Cp & TgCDPK1) can be selectively targeted with so-called Bumped Kinase Inhibitors (BKIs) that do not inhibit mammalian kinases, and these BKIs prevent the growth of cryptosporidium and toxoplasma. The BKIs have good oral bioavailability, pharmacokinetic, and are easy to synthesize. One of our lead BKIs has been shown to have efficacy in mouse models of cryptosporidiosis and toxoplasmosis. Thus BKIs are now excellent lead candidates for drug development for the therapy of cryptosporidiosis and toxoplasmosis. This proposal is to move the BKIs through pre-clinical development and select a clinical candidate. The goal of this project is to have a clinical candidate for the therapy of cryptosporidiosis and toxoplasmosis that is ready to undergo FDA IND review, with 1-2 compounds as backups.